In the medical field, catheters are generally used to drain fluids from a body cavity. In the urology field, a Foley retention drainage catheter, which may be interchangeably referred to as a Foley catheter or drainage catheter, is commonly used to drain a human bladder. There are many medical conditions that necessitate the use of a Foley catheter. The collection of urine and other fluids after a surgical procedure is such a condition. For the past seventy to eighty years the Foley retention drainage catheter, as depicted in FIG. 18 and labeled “PRIOR ART,” has been the preferred option to drain and collect urine and other fluids from the bladder. The basic design of a Foley catheter comprises an elongated cylindrical element containing a central drainage lumen running the length of the elongated cylindrical element, having one or more drainage ports in series at or near the distal end, and an expandable retention element, located proximal to the drainage ports, for securing the catheter within the bladder. The retention element is expanded with fluid via an inflation lumen running from the inflation valve located on the proximal end of the elongated cylindrical element to the retention element. The design of the Foley catheter has not undergone significant changes other than changes to the base materials and attempts to give the materials antibacterial properties. Despite its continued use in the health care industry without significant design changes the Foley catheter does have some acknowledged weaknesses.
Firstly, the Foley catheter is susceptible to obstruction of the drainage ports and the drainage lumen of the catheter due to plugging and/or buildup of debris (debris is defined as loose tissue, sediments, clotted blood, redundant bladder mucosa, and any other materials or viscous fluids in the clinical setting). The drainage ports are generally at least twice the cross sectional area of the drainage lumen. This can result in a funneling effect with debris draining into smaller and smaller spaces, thus, resulting in plugs and blockages causing catheter obstruction. Further, due to the drainage ports being in series, if the most proximal drainage port becomes obstructed by debris that extend from the port into the drainage lumen, thus obstructing the drainage lumen, any remaining unobstructed drainage ports are rendered ineffective as they are upstream of the obstruction. Incomplete emptying/drainage of the bladder caused by obstructions in the catheter are significant causes of catheter associated urinary tract infections (UTIs).
Secondly, the drainage ports in the catheter, being limited in number and limited in cumulative cross sectional area as related to the cross sectional area of the drainage lumen, create a suction effect so that when the force of the suction is projected on the bladder mucosa the suction can cause a disruption in the mucosal integrity. This can result in increased risk of pain, bladder spasms, discomfort, and catheter associated UTIs.
Thirdly, yet another problem is the inability of the Foley catheter to completely drain the bladder, even when the drainage system is completely free of obstruction. Due to the aforementioned drainage port locations, when the bladder is actively drained during catheterization, and the bladder wall closes around the retention element, the bladder retains a residual volume of fluid that is not able to reach the drainage ports. This volume of stagnant fluid can contain urine, blood, bacteria, and/or other pathogens that, when not regularly flushed out of the bladder, can set up an infection in the surrounding tissues, form blood clots in the bladder, and/or other conditions detrimental to the patient. It should be understood that catheter associated UTIs are now the most expensive hospital acquired infection according to the Centers for Disease Control and Prevention.